FINANCIAL DERIVATIVES - Schedule of Derivative Instruments in Statement of Financial Position (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Notional Disclosures [Abstract]
Notional Amount	$ 25,456,600	$ 25,779,468
Asset
Fair value, asset	49,197	37,478
Netting adjustments	(8,595)	(1,236)
(Liability)
Fair value, liability	(64,351)	(117,131)
Netting adjustments	8,595	1,236
Designated as hedge | Fair value hedges: | Receive fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	8,363,185	9,174,253
Asset
Fair value, asset	770	7,767
(Liability)
Fair value, liability	$ (19,533)	$ (1,081)
Weighted- Average Pay Rate	5.17%	2.50%
Weighted- Average Receive Rate	3.36%	5.47%
Weighted- Average Remaining Term (in years)	1 year 6 months 25 days	9 years 6 months 25 days
Designated as hedge | Fair value hedges: | Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 9,679,159	$ 9,776,685
Asset
Fair value, asset	21,625	2,350
(Liability)
Fair value, liability	$ (24)	$ (20,390)
Weighted- Average Pay Rate	2.66%	5.57%
Weighted- Average Receive Rate	5.03%	2.94%
Weighted- Average Remaining Term (in years)	9 years 3 months	1 year 9 months 10 days
Designated as hedge | Fair value hedges: | Receive fixed callable
Notional Disclosures [Abstract]
Notional Amount	$ 4,090,827	$ 3,879,827
Asset
Fair value, asset	19,612	7,374
(Liability)
Fair value, liability	$ (52,594)	$ (95,984)
Weighted- Average Pay Rate	5.00%	5.40%
Weighted- Average Receive Rate	3.50%	3.40%
Weighted- Average Remaining Term (in years)	2 years 6 months 25 days	2 years 5 months 23 days
Designated as hedge | Cash flow hedges: | Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 540,000	$ 558,000
Asset
Fair value, asset	14,900	20,234
(Liability)
Fair value, liability	$ 0	$ (43)
Weighted- Average Pay Rate	1.92%	1.94%
Weighted- Average Receive Rate	5.35%	5.82%
Weighted- Average Remaining Term (in years)	3 years 8 months 4 days	4 years 3 months 18 days
No hedge designation | Receive fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 1,926,269	$ 1,358,396
Asset
Fair value, asset	5	263
(Liability)
Fair value, liability	$ (243)	$ (3)
Weighted- Average Pay Rate	4.99%	5.44%
Weighted- Average Receive Rate	4.80%	4.87%
Weighted- Average Remaining Term (in years)	3 months 25 days	7 months 20 days
No hedge designation | Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 157,776	$ 160,623
Asset
Fair value, asset	720	676
(Liability)
Fair value, liability	$ (4)	$ (29)
Weighted- Average Pay Rate	2.92%	2.92%
Weighted- Average Receive Rate	5.22%	5.64%
Weighted- Average Remaining Term (in years)	3 years 7 months 24 days	4 years 4 months 2 days
No hedge designation | Basis swaps
Notional Disclosures [Abstract]
Notional Amount	$ 655,384	$ 850,384
Asset
Fair value, asset	21	39
(Liability)
Fair value, liability	$ (548)	$ (746)
Weighted- Average Pay Rate	5.16%	5.52%
Weighted- Average Receive Rate	5.01%	5.48%
Weighted- Average Remaining Term (in years)	4 years 29 days	3 years 9 months 29 days
No hedge designation | Treasury futures
Notional Disclosures [Abstract]
Notional Amount	$ 44,000	$ 21,300
Asset
Fair value, asset	139	11
Netting adjustments	(8,595)	(1,236)
(Liability)
Fair value, liability	0	(91)
Netting adjustments	$ 8,595	$ 1,236
Weighted- Average Forward Price (in dollars per share)	$ 114.60	$ 112.51